Rainbow Shark
Epalzeorhynchos frenatum
Also sold as Red-finned shark · Albino rainbow shark · GloFish shark
Synonyms Ruby shark
Rainbow Shark (Epalzeorhynchos frenatum) is a semi-aggressive freshwater fish that reaches about 15 cm (5.9 in) and swims in open water. It wants 68–79°F (20–26°C) and pH 6.5–8, can be kept singly, and needs a tank of at least 243 L (64 gal).
At a glance
| Type | Fish |
|---|---|
| Adult size | 15 cm (5.9 in) |
| Minimum tank | 243 L (64 gal) |
| Group size | Can be kept singly |
| Temperature | 68–79°F (20–26°C) |
| pH | 6.5–8 |
| Temperament | Semi-aggressive |
| Lifespan | 5–8 years |
| Eats shrimp | Yes |
Before it goes in
- Rainbow Shark needs at least 243 L (64 gal). The smallest size in this library that clears that is the 120P.
- It eats shrimp. Cherry Shrimp, Crystal Red Shrimp and Bamboo Shrimp are on the menu.
- It is the wrong size to share a tank with Iridescent Shark, Senegal Bichir and Black Ghost Knifefish: it ends up as food.
- It holds at 68–79°F (20–26°C). That shares a window with Betta and Cherry Shrimp, but not with Discus.
- It is semi-aggressive — plan the tank around it rather than adding it to a finished community.
- Sources say not to put it in a newly set-up tank — give the tank a few months first.
What tank size does it need?
At least 243 L (64 gal). The smallest size here that clears it is the 120P.
Will it eat shrimp?
Yes. Shrimp are food to it, so pick one or the other.
What water does it want?
68–79°F (20–26°C), pH 6.5–8.
How long does it live?
5–8 years in a tank that suits it. That is how long you are signing up for.
Can it go in a new tank?
No. Sources say not to add it to a newly set-up tank — it wants a tank that has been running for months.
Good tank mates
- Tank mates from this library that share its temperature window, are peaceful and eat neither it nor its young: Goldfish, Bristlenose Pleco, Celestial Pearl Danio, Molly and Otocinclus.
- Plants that hold up with it: Hygrophila corymbosa 'Siamensis', Water Sprite, Anubias nana 'Petite' and Cryptocoryne wendtii.
Often compared with
| Rainbow Shark | Red Tail Shark | Flying Fox | |
|---|---|---|---|
| Adult size | 15 cm | 12.5 cm | 16 cm |
| Min tank | 243 L | 243 L | 243 L |
| Group | 1+ | 1+ | 1+ |
| Temperature | 68–79°F (20–26°C) | 68–79°F (20–26°C) | 68–79°F (20–26°C) |
| Eats shrimp | Yes | Yes | Yes |
More livestock
Sources (4) · checked Sep 2026
- Mature tank, Temperamentseriouslyfish.com
- What it eatsaquaticarts.com
- What it eatsseriouslyfish.com
- tankarium.com